RKI Instruments M2A Series Owner's manual

RKI Instruments, Inc.

www.rkiinstruments.com

M2A Transmitter

Operator’s Manual

Part Number: 71-0305RK

Revision: P

Released: 8/28/20

M2A Transmitter Operator’s Manual

WARNING

Read and understand this instruction manual before operating instrument.

Improper use of the gas monitor could result in bodily harm or death.

Periodic calibration and maintenance of the gas monitor is essential for proper

operation and correct readings. Please calibrate and maintain this instrument

regularly! Frequency of calibration depends upon the type of use you have and

the sensor types. Typical calibration frequencies for most applications are

between 3 and 6 months, but can be required more often or less often based on

your usage.

M2A Transmitter Operator’s Manual

Product Warranty

RKI Instruments, Inc. warrants gas alarm equipment sold by us to be free from defects in materials,

workmanship, and performance for a period of one year from date of shipment from RKI Instruments, Inc. Any

parts found defective within that period will be repaired or replaced, at our option, free of charge. This warranty

does not apply to those items which by their nature are subject to deterioration or consumption in normal service,

and which must be cleaned, repaired, or replaced on a routine basis. Examples of such items are:

Warranty is voided by abuse including mechanical damage, alteration, rough handling, or repair procedures not

in accordance with the operator’s manual. This warranty indicates the full extent of our liability, and we are not

responsible for removal or replacement costs, local repair costs, transportation costs, or contingent expenses

incurred without our prior approval.

THIS WARRANTY IS EXPRESSLY IN LIEU OF ANY AND ALL OTHER WARRANTIES

AND REPRESENTATIONS, EXPRESSED OR IMPLIED, AND ALL OTHER

OBLIGATIONS OR LIABILITIES ON THE PART OF RKI INSTRUMENTS, INC.

INCLUDING BUT NOT LIMITED TO, THE WARRANTY OF MERCHANTABILITY OR

FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL RKI INSTRUMENTS,

INC. BE LIABLE FOR INDIRECT, INCIDENTAL, OR CONSEQUENTIAL LOSS OR

DAMAGE OF ANY KIND CONNECTED WITH THE USE OF ITS PRODUCTS OR

FAILURE OF ITS PRODUCTS TO FUNCTION OR OPERATE PROPERLY.

This warranty covers instruments and parts sold to users by authorized distributors, dealers, and representatives

as appointed by RKI Instruments, Inc.

We do not assume indemnification for any accident or damage caused by the operation of this gas monitor, and

our warranty is limited to the replacement of parts or our complete goods.

a) Absorbent cartridges d) Batteries

b) Pump diaphragms and valves e) Filter elements

c) Fuses

M2A Transmitter Operator’s Manual

Table of Contents

Chapter 1: Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

About the M2A Transmitter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

About this Manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Chapter 2: Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

External Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Internal Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Chapter 3: Installation & Startup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Mounting the M2A Transmitter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Wiring the M2A Transmitter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

Start Up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

Chapter 4: Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

Normal Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

Information Screen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

4 - 20 mA Signal Output Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

Alarm Indications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

Chapter 5: Configuration Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

Viewing & Changing M2A Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

Chapter 6: Gas Type Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

Selecting the Gas Type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

M2A Transmitter Operator’s Manual

Chapter 7: Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

Overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

Preventive Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

Calibration Frequency. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

Calibration, Combustible Gas, CO

2

, and Toxic Versions . . . . . . . . . . . . . . . 50

Calibration, Oxygen Version . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

Replacing Components of the M2A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

Chapter 8: RS-485 Modbus Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61

Overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61

Wiring the M2A in a Modbus System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61

Using the M2A in a 4-wire Modbus System. . . . . . . . . . . . . . . . . . . . . . . . . . 64

Modbus Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64

Supported Modbus Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66

Chapter 9: Parts List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71

Appendix A: Control Button Quick Reference Guide. . . . . . . . . . . . . . . . . . . . . . 76

Appendix B: PLC and DCS Device Wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77

Appendix C: Function Code 16 Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79

6 M2A Transmitter Operator’s Manual

Chapter 1: Introduction

Overview

This chapter briefly describes the M2A Transmitter. This chapter also describes the M2A Transmitter Operator’s

Manual (this document). Table 1 at the end of this chapter lists the specifications for the M2A.

About the M2A Transmitter

The M2A transmitter is a fixed mount, continuous-monitoring detector head. All user adjustable parameters may

be accessed using push button switches. In addition, calibration may be performed non-intrusively by use of a

magnetic wand accessory which activates magnetic switches through a window at the front face of the detector

head.

The M2A displays the current gas reading on an OLED display which is visible through the window in the cover

(front face) and provides a 4 - 20 mA signal which indicates the target gas reading for use by a gas monitoring

controller, recording device, or programmable controller. The M2A also provides an RS-485 Modbus output.

Three sets of relay contacts, two controlled by the gas alarms and one by the fail alarm, rated at 115 VAC 5 amps

are available for controlling devices such as lights or horns or for controlling higher rated relays.

Four operating modes allow you to display and change setup and calibration settings and change the gas type.

They are Calibration Mode, Configuration Mode, Gas Type Mode, and Modbus Mode.

About this Manual

The M2A Transmitter Operator’s Manual uses the following conventions for notes, cautions, and warnings.

NOTE: Describes additional or critical information.

CAUTION: Describes potential damage to equipment.

WARNING: Describes potential danger that can result in injury or death.

M2A Transmitter Operator’s Manual 7

Specifications

Table 1 lists specifications for the M2A.

Table 1: M2A Specifications

Target Gas/

Detection Range

Combustible Gas/Carbon Dioxide (CO

2

)

• Catalytic LEL: 0 - 100% LEL, 1% LEL increments (CH

4

calibration unless otherwise

specified. H

2

specific detector available)

• Catalytic CH

4

ppm: 0 - 9000 ppm, 20 ppm increments

• IR (infrared) CH

4

LEL: 0 - 100% LEL, 1% LEL increments

• IR HC LEL: 0 - 100% LEL, 1% LEL increments (propane calibration)

•IR CH

4

Volume: 0 - 5.00% volume, 0.01% increments

•IR CH

4

Volume: 0 - 100 % volume, 1% increments

•IR CO

2

ppm: 0 - 5,000 ppm, 20 ppm increments

•IR CO

2

ppm: 0 - 10,000 ppm, 20 ppm increments

•IR CO

2

Volume: 0 - 5.00 % volume, 0.01% increments

•IR CO

2

Volume: 0 - 50.0 % volume, 0.1% increments

•IR CO

2

Volume: 0 - 100 % volume, 1% increments

Oxygen

• Oxygen (O

2

): 0 - 25.0 % volume, 0.1% increments

CO/H

2

S

• Carbon Monoxide (CO): 0 - 300 ppm, 1 ppm increments

• Carbon Monoxide (CO): 0 - 200 ppm, 1 ppm increments

• Carbon Monoxide (CO): 0 - 100 ppm, 1 ppm increments

• Hydrogen Sulfide (H

2

S): 0 - 100 ppm, 1 ppm increments

• Hydrogen Sulfide (H

2

S): 0 - 50 ppm, 0.1 ppm increments

Tox ic

• Ammonia (NH

3

): 0 - 75.0 ppm, 0.1 ppm increments

• Ammonia (NH

3

): 0 - 100 ppm, 1 ppm increments

• Ammonia (NH

3

): 0 - 500 ppm, 1 ppm increments

• Arsine (AsH

3

): 0 - 1.50 ppm, 0.01 ppm increments

• Chlorine (Cl

2

): 0 - 3.00 ppm, 0.01 ppm increments

• Chlorine (Cl

2

): 0 - 10.0 ppm, 0.1 ppm increments

• Chlorine Dioxide (ClO

2

): 0 - 1.00 ppm, 0.01 ppm increments

• Chlorine Dioxide (ClO

2

): 0 - 3.00 ppm, 0.01 ppm increments

• Hydrogen Cyanide (HCN): 0 - 15.0 ppm, 0.1 ppm increments

• Phosphine (PH

3

): 0 - 1.00 ppm, 0.01 ppm increments

• Sulphur Dioxide (SO

2

): 0 - 6.00 ppm, 0.01 ppm increments

Alarm Settings

(Alarm 1/Alarm 2)*

Ammonia (0 - 75.0 ppm and

0 - 100 ppm): 12 ppm / 25 ppm

Ammonia (0 - 200 ppm): 25 ppm / 35 ppm

Ammonia (0 - 500 ppm): 35 ppm / 300 ppm

Arsine: 0.20 ppm / 0.50ppm

Carbon Dioxide (0 - 5,000 ppm): 2,500 ppm / 5,000 ppm

Carbon Dioxide (0 - 9,000 ppm): 2,000 ppm / 5,000 ppm

Carbon Dioxide (0 - 5.00%): 0.50 % / 3.00 %

Carbon Dioxide (0 - 50.0%): 50.0% / 50.0%

Carbon Dioxide (0 - 100%): 100% / 100%

Carbon Monoxide (all ranges): 25 ppm / 50 ppm

Chlorine (0 - 3.00 ppm): 0.50 ppm / 1.00 ppm

Chlorine (0 - 5.00 ppm): 0.50 ppm / 1.50 ppm

Chlorine (0 - 10.0 ppm): 1.0 ppm / 3.0 ppm

8 M2A Transmitter Operator’s Manual

Alarm Settings

(Alarm 1/Alarm 2)*,

cont’d

Chlorine Dioxide (0 - 1.00 ppm): 0.10 ppm / 0.30 ppm

Chlorine Dioxide (0 - 3.00 ppm): 0.30 ppm / 1.00 ppm

Chlorine Dioxide (0 - 5.00 ppm): 0.50 ppm / 1.00 ppm

Combustible Gas (%LEL): 10 %LEL / 50 %LEL

Combustible Gas (0-100%Volume): 100 % / 100 %

Hydrogen Cyanide: 5.0 ppm / 10.0 ppm

Hydrogen Sulfide (0 - 50 ppm): 5.0 ppm / 10.0 ppm

Hydrogen Sulfide (0 - 100 ppm): 10 ppm / 50 ppm

Methane (ppm): 5000 ppm / 8000 ppm

Methane (0-5.00%Volume): 0.5% / 2.5 %

Oxygen: 19.5% (decreasing) / 23.5% (increasing)

Phosphine: 0.10 ppm / 0.30 ppm

Sulphur Dioxide: 1.00 ppm / 2.00 ppm

Construction (housing) Explosion-proof Junction Box, NEMA 4X

Area Classification Explosion-proof for Class I, Groups B, C, and D (Combustible, CO

2

, CSA Type CO and H

2

S,

and CSA Type oxygen)

Sampling Method Diffusion

Input Power 10 - 30 VDC

Controls • Three push button switches

• Three magnetic switches for non-intrusive calibration

Weight 4.5 lbs.

Signal Output • 4 to 20 mA with impedance maximums listed below

-12 VDC input: 500 ohms impedance max

-24 VDC input: 1000 ohms impedance max

• RS-485 Modbus

Explosion Proof Non-Explosion Proof

Operating Temperature

Catalytic LEL/ppm -40°C to 75°C N/A

Oxygen -20°C to 45°C -20°C to 50°C

H

2

S -40°C to 40°C -40°C to 50°C

CO -5°C to 40°C -20°C to 50°C

Toxic (ESM-01) N/A -10°C to 40°C

Tox ic (CT-7 Seri es ) N/A -20°C to 40°C

Infrared Combustible -20°C to 50°C -40°C to 50°C

Infrared CO

2

-20°C to 50°C -40°C to 50°C

Table 1: M2A Specifications

M2A Transmitter Operator’s Manual 9

WARNING: When using the M2A, you must follow the instructions and warnings in this manual to

assure proper and safe operation of the M2A and to minimize the risk of personal injury. Be

sure to maintain and periodically calibrate the M2A as described in this manual.

Accuracy Catalytic Combustible Gas (LEL range):

± 5% of reading or ± 2% LEL (whichever is greater)

Catalytic CH

4

(ppm range):

± 5% of reading or ± 50 ppm (whichever is greater)**

IR Combustible Gas/IR CO

2

:

± 5% of reading or ± 2% of full scale (whichever is greater)

Oxygen

:

± 0.5% O

2

Hydrogen Sulfide:

± 5% of reading or ± 2 ppm H

2

S (whichever is greater)

Carbon Monoxide

:

± 5% of reading or ± 5 ppm CO (whichever is greater)

Toxic Sensors (ESM-01 Type and CT-7 Series Type)

:

± 10% of reading or ± 5% of full scale (whichever is greater)

*

These are RKI factory settings. See “Viewing & Changing M2A Parameters” on page 42 to change the alarm settings.

**

Independent of zero drift.

Table 1: M2A Specifications

10 M2A Transmitter Operator’s Manual

Chapter 2: Description

Overview

This chapter describes external and internal components of the M2A Transmitter.

External Description

This section describes the junction box and all external components of the M2A transmitter.

Figure 1: M2A External Components

Junction Box

The M2A’s cast aluminum junction box is dust and weather resistant. The junction box also protects the M2A

and all connections made to it. Use the three 3/4 NPT conduit ports to mount the detector to the junction box

(factory installed in the bottom port) and connect wiring from an external device (left port). The top port is

shipped with a factory installed and sealed conduit plug to avoid leaks into the junction box. If necessary, the

conduit plug can be removed and the top port can be used for wiring.

WARNING: If the top conduit port is used for wiring, be sure to seal the threads to ensure water does not

enter the junction box. See “Wiring the M2A Transmitter” on page 28 for complete wiring

instructions.

Use the junction box’s two mounting holes to mount the M2A to a vertical surface at the monitoring site. The

window in the cover on the front of the junction box allows you to view the OLED display and use the magnetic

wand to actuate the magnetic control switches so you can perform non-intrusive calibration. Removing the cover

Magnetic

Wand

Junction Box Cover

3/4 NPT Conduit Port, Plugged

3/4 NPT

Conduit Port

Window

Mounting Slot (2x)

Detector

(Catalytic LEL Detector Shown)

M2A Transmitter Operator’s Manual 11

allows you to access the interior of the junction box.

Magnetic Wand

The magnetic wand is a short plastic rod with a magnet in one end. It is used to actuate the magnetic control

switches on the control PCB while the junction box cover is still installed so that non-intrusive calibration can be

performed.

Gas Detector

The gas detector senses the target gas and is mounted in a 3/4 NPT conduit port on the right bottom side of the

M2A. A variety of detectors may be used with the M2A. See the sections below for descriptions of each type of

detector.

Catalytic Detectors

The catalytic detectors have a 1/2 NPT thread and require a 3/4 NPT x 1/2 NPT reducer to install in the detector

port.

The table below outlines the M2A part numbers and replacement detector part numbers for the catalytic

detectors.

Table 2: Catalytic Detectors

Figure 2: Catalytic Sensors

Target Gas, Range M2A Part Number Detector Used

Combustible Gas, 0 - 100% LEL 65-2640RK 61-0140RK (Catalytic UL version)

65-2640RK-05 61-0140RK-05 (Catalytic CSA version)

Hydrogen, 0 - 100% LEL 65-2641RK NC-6205-01 (Catalytic UL version, hydrogen specific)

65-2641RK-05 NC-6205-05 (Catalytic CSA version, hydrogen specific)

Methane, 0 - 9000 ppm 65-2647RK 61-0140RKA (Catalytic UL version)

65-2647RK-05 61-0140RKA-05 (Catalytic CSA version)

Detector PartNumbers

61-0140RK

61-0140RKA

NC-6205-01

UL Version

Detector PartNumbers

61-0140RK-05

61-0140RKA-05

NC-6205-05

CSA

Version

12 M2A Transmitter Operator’s Manual

Infrared (IR) Detectors

The IR combustible detectors are generally used instead of the catalytic combustible detectors in applications

where there may be catalyst poisons such as silicone present or where oxygen is not present in the monitoring

environment.

The table below outlines the M2A part numbers and replacement detector part numbers for the infrared (IR)

detectors.

Table 3: Infrared (IR) Detectors

Target Gas, Range M2A Part Number Detector Used

CH

4

, 0 - 100% LEL 65-2649RK-CH4 61-0190RK-CH4 (UL)

65-2664RK-CH4 61-0197RK-CH4

CH

4

, 0 - 5.00% volume 65-2649RK-CH4-5 61-0190RK-CH4 (UL)

CH

4

, 0 - 100% volume 65-2658RK-CH4 61-0192RK-CH4 (UL)

65-2665RK-CH4 61-0199RK-CH4

CO

2

, 0 - 5,000 ppm 65-2660RK-02 61-0191RK-02 (UL)

65-2661RK-02 61-0198RK-02

CO

2

, 0 - 9,000 ppm 65-2660RK-01 61-0191RK-01 (UL)

65-2661RK-01 61-0198RK-01

CO

2

, 0 - 5% volume 65-2660RK-03 61-0191RK-03 (UL)

65-2661RK-03 61-0198RK-03

CO

2

, 0 - 50% volume 65-2660RK-05 61-0191RK-05 (UL)

65-2661RK-05 61-0198RK-05

CO

2

, 0 - 100% volume 65-2660RK-10 61-0191RK-10 (UL)

65-2661RK-10 61-0198RK-10

HC, 0 - 100% LEL (cal. to propane) 65-2649RK-HC 61-0190RK-HC (UL)

65-2664RK-HC 61-0197RK-HC

M2A Transmitter Operator’s Manual 13

Figure 3: Infrared (IR) Sensors

Oxygen Detectors

There are three types of oxygen detectors available: a non-explosion proof partial pressure type, a non-explosion

proof capillary type with a replaceable sensor, and an explosion proof (CSA) capillary type with a replaceable

sensor. The capillary type’s output is less susceptible to variations in atmospheric pressure than the partial

pressure type. The CSA type oxygen detector (65-2514RK) and the non-explosion proof capillary type detector

(65-2494RK) has a replaceable plug-in sensor inside the detector housing. The entire oxygen detector must be

removed if replacement is required for the 65-2510RK.

The table below outlines the M2A part numbers and replacement detector part numbers for the oxygen detectors.

Table 4: Oxygen Detectors

Target Gas, Range M2A Part Number Detector Used

Oxygen, 0 - 25% 65-2643RK-05 65-2514RK (capillary, CSA)

65-2644RK 65-2510RK (partial pressure)

65-2666RK 65-2494RK (capillary)

Detector Housing Body

Cap Gasket

Plug-In IR LEL Sensor

Detector Housing Cap

Non-XP, Replaceable-SensorType

Hydrophobic

Membrane

XP, Non-Replaceable-

Sensor Type

Detector PartNumbers

61-0197RK-CH4

61-0197RK-HC

61-0198RK-01

61-0198RK-02

61-0198RK-03

61-0198RK-05

61-0198RK-10

61-0199RK-CH4

Detector PartNumbers

61-0190RK-CH4

61-0190RK-HC

61-0191RK-01

61-0191RK-02

61-0191RK-03

61-0191RK-05

61-0191RK-10

61-0192RK-CH4

61-0192-HC

14 M2A Transmitter Operator’s Manual

Figure 4: Oxygen Detectors

CO and H

2

S Detectors

Both types of CO and H

2

S detectors (explosion-proof and non-explosion-proof) have replaceable plug-in sensors

inside the detector housing.

The CO detectors include a charcoal filter disk which is held onto the sensor with a rubber retaining boot. The

charcoal filter disk scrubs out interfering gases to which the CO sensor responds such as H

2

S and certain

hydrocarbons.

The 65-2428 and 65-2428-01 explosion-proof H

2

S detectors both include a rubber boot and a spacer which help

ensure that the sensor remains plugged into the detector housing body. The only difference between the 65-2428

and the 65-2428-01 is that the sensor used in the 65-2428-01 is resistant to degradation caused by frequent

exposure to low levels of H

2

S or occasional exposure to high levels of H

2

S.

The 65-2495RK non-explosion-proof H

2

S detector includes an adhesive-backed gasket inside the detector

housing cap which helps ensure that the sensor remains plugged into the detector housing body.

The table below outlines the M2A part numbers and replacement detector part numbers for the CO and H

2

S

detectors.

Table 5 : CO and H

2

S Detectors

Target Gas, Range M2A Part Number Detector Used

CO, 0 - 300 ppm 65-2646RK-05 65-2438 (CSA)

65-2663RK 65-2496RK

CO, 0 - 200 ppm 65-2646RK-05-02 65-2438-01

CO, 0 - 100 ppm 65-2646RK-05-01 65-2438-01

H

2

S, 0 - 100 ppm 65-2645RK-05 65-2428 (CSA)

65-2645-05-07 65-2428-01 (CSA)

65-2662RK 65-2495RK

Cap Gasket

Detector Housing Body

Detector

Housing Cap

Hydrophobic

Membrane

Detector

Housing Cap

Plug-In Oxygen

Sensor

Cap Gasket

Non-XP,

Replaceable-Sensor Capillary Type

Non-XP, Partial

Pressure Type

Oxygen Sensor

Detector Housing Body

Flame

Arrestor

Guard

Detector

PartNumber

65-2494RK

Detector Part

Number

65-2510RK

Detector PartNumber

65-2514RK

XP,

Replaceable-Sensor CapillaryType

M2A Transmitter Operator’s Manual 15

Figure 5: H

2

S Detectors

Figure 6: CO Detectors

Cap Gasket

Flame

Arrestor

Guard

H2S Plug-in Sensor

Spacer

Rubber Boot

Detector

Housing Cap

Non-XP Type

Detector

Housing Cap

Hydrophobic

Membrane

Cap Gasket

H2S Plug-in Sensor

Detector Housing Body

Detector Part Number

65-2495RK

Detector Part Numbers

65-2428

65-2428-01

Detector Housing Body

XP Type

Detector

Housing Cap

Charcoal Filter

w/Rubber Boot

CO Plug-in Sensor

Cap Gasket

Detector Housing Body

Cap Gasket

Hydrophobic

Membrane

CO Plug-in Sensor

Flame

Arrestor

Guard

Detector

Housing Cap

Non-XP Type

Detector PartNumber

65-2496RK

Detector Housing Body

Rubber Boot w/

Charcoal Filter

XP Type

Detector PartNumber

65-2438

65-2438-01

16 M2A Transmitter Operator’s Manual

ESM-01 Detectors

The construction of the various ESM-01 detectors is similar. Each of the ESM-01 detectors has a different

replaceable plug-in sensor that protrudes through the detector housing cap. Although ESM-01 detectors look the

same except for the plug-in detector, the detector housing which includes the detector socket and conditioning

circuitry is specific to a sensor type. For example, a detector housing from a Cl

2

detector cannot be used with an

NH

3

detector. One of the two detector wires is color coded for each specific detector type. The ESM-01 detectors

include a removable splashguard that screws onto the detector housing cap. When it is necessary to apply gas to

an ESM-01 detector, remove the splashguard to allow access to the sensor that protrudes through the detector

housing cap. You can then push the appropriate ESM-01 calibration cup onto the sensor.

The table below outlines the M2A part numbers and replacement detector part numbers for the ESM-01

detectors.

Table 6: ESM-01 Detectors

Figure 7: ESM-01 Type Detector

Target Gas, Range M2A Part Number Detector Used

AsH

3

, 0 - 1.5 ppm 65-2648RK-ASH3 65-2300RK-ASH3

Cl

2

, 0 - 3 ppm 65-2648RK-CL2 65-2300RK-CL2

Cl

2

, 0 - 10 ppm 65-2648RK-CL-10 65-2300RK-CL-10

HCN, 0 - 15 ppm 65-2648RK-HCN 65-2300RK-HCN

NH

3

, 0 - 75 ppm 65-2648RK-NH3 65-2300RK-NH3

PH

3

, 0 - 1 ppm 65-2648RK-PH3 65-2300RK-PH3

SO

2

, 0 - 6 ppm 65-2648RK-SO2 65-2300RK-SO2

Splash Guard

(removable)

Cap Gasket

Detector Housing Body

(different for each detector type)

Sensor

(different for each detector type)

Detector Housing

Cap

M2A Transmitter Operator’s Manual 17

CT-7 Series Detectors

The CT-7 Series detectors for Cl

2

and ClO

2

have a replaceable plug-in sensor inside the detector housing. An

adhesive backed gasket inside the detector housing cap helps ensure that the sensor remains plugged into the

detector housing body.

The table below outlines the M2A part numbers and replacement detector part numbers for the CT-7 Series

detectors.

Table 7: CT-7 Series Detectors

Figure 8: CT-7 Series Detectors

Target Gas, Range M2A Part Number Detector Used

Cl

2

, 0 - 3 ppm 65-2670-CL2 65-2302-CL2

Cl

2

, 0 - 5 ppm 65-2670-CL2-5 65-2302-CL2-5

Cl

2

, 0 - 10 ppm 65-2670-CL2-10 65-2302-CL2-10

ClO

2

, 0 - 1 ppm 65-2670-CLO2 65-2302-CLO2

ClO

2

, 0 - 3 ppm 65-2670-CLO2-3 65-2302-CLO2-3

ClO

2

, 0 - 5 ppm 65-2670-CLO2-5 65-2302-CLO2-5

NH

3

, 0 - 75.0 ppm 65-2670-NH3 65-2302-NH3

NH

3

, 0 - 100 ppm 65-2670-NH3-1 65-2302-NH3-1

NH

3

, 0 - 200 ppm 65-2670-NH3-2 65-2302-NH3-2

NH

3

, 0 - 500 ppm 65-2670-NH3-5 65-2302-NH3-5

Hydrophobic Membrane

Plug-in Sensor

Detector

Housing Cap

Cap Gasket

Detector Housing Body

(different for each detector type)

18 M2A Transmitter Operator’s Manual

Internal Description

This section describes the internal components of the M2A. The internal components of the M2A include the

terminal PCB which provides for all the wiring connections to the M2A and the control PCB which displays the

gas reading and has the control buttons.

Figure 9: M2A Internal Components

Terminal PCB

The terminal PCB is encapsulated in epoxy for protection against moisture and physical damage. It is mounted

into the rear of the junction box with three standoffs and rests on a thin layer of foam. A banana jack is screwed

into each of the standoffs and is used for mounting the control PCB. The terminal PCB converts the electrical

output from the detector to a signal which can be displayed by the OLED display, a 4 - 20 mA signal (that is

proportional to the detection range), and an RS-485 Modbus output signal. The 4 - 20 mA signal may be used by

a recording device, gas monitor controller, or programmable controller. The Modbus output may be used to

connect the M2A to a Modbus network. The terminal PCB also controls three relays: one fail and two gas alarm.

Two columns of plug-in style terminal strips are used to make all wiring connections to the M2A. The column on

the left consists of the power/signal, detector, and Modbus terminal strips. The column on the right consists of

the relay terminal strips. A 20 position connector at the bottom of the terminal PCB is used to connect the

terminal PCB to the control PCB with a ribbon cable. A 5 position connector on the left side of the terminal PCB

is used by factory or field service personnel to program the M2A. On the combustible and CO

2

versions of the

M2A, a factory adjust pot just above the programming connector is used to set the detector current.

NO

Control PCB

Junction Box

Terminal PCB

3/4 NPT Conduit

Opening for Wire Entry

M2A TRANSMITTER

RKI INSTRUMENTS

3/4 NPT Conduit Opening, Plugged

M2A Transmitter Operator’s Manual 19

Figure 10: Terminal PCB Component Location

Power/Signal Terminal Strip

The power/signal terminal strip is a three position plug-in style terminal strip located at the top of the left

terminal column. It is used to connect 24 VDC power to the M2A and to connect the 4 - 20 mA output signal to a

device.

The signal output, the S terminal, does not have to be connected for the M2A to function. The S terminal is used

if you want to connect the 4 - 20 mA output signal to another device such as a gas monitoring controller, chart

recorder, or programmable controller (PLC).

Detector Terminal Strip

The detector terminal strip is a four position plug-in style terminal strip and is the middle terminal strip in the left

terminal column. For a combustible or CO

2

M2A, all four terminals are used to connect the detector to the M2A.

For a toxic or oxygen M2A, only two of the terminals are used for connecting a detector; two terminals are

dedicated for connecting a toxic detector and two are dedicated for connecting an oxygen detector (only one

detector can be installed).

Figure 11: Detector Terminal Strip

- S +

A B C

RS 485 PWR/SIG

R W G B

LEL

C NC NO

ALARM 1

C NC NO

ALARM 2

C NC NO

FAIL

Modbus Terminal Strip

Ground Jumper

Programming Connector

(Factory Use)

Power/Signal Terminal Strip

Termination Jumper

Ribbon Cable Connector

Detector Current Adjust Pot

(Comb/CO2 Type Only, Factory Adjust)

Detector Terminal Strip

(Comb/CO2 Version Shown)

Relay

Terminal

Strips

Toxic/Oxy

Detector

Terminal

Strip

Comb/CO2

Detector

Terminal

Strip

- S +

PWR/SIG

TOXIC OXY

+ - + -

RS 485

A B C

C NC NO

ALARM 1

C NC NO

ALARM 2

C NC NO

FAIL

- S +

A B C

RS 485 PWR/SIG

R W G B

LEL

C NC NO

ALARM 1

C NC NO

ALARM 2

C NC NO

FAIL

20 M2A Transmitter Operator’s Manual

NOTE: The detector is factory-wired to the M2A. See “Wiring the M2A Transmitter” on page 28 for all

wiring procedures related to M2A.

Modbus Terminal Strip

The Modbus terminal strip is a three position plug-in style terminal strip and is the bottom terminal strip in the

left terminal column. It allows connection of the M2A into a Modbus network.

Relay Terminal Strips

The right column of terminal strips consists of, from top to bottom, the fail, alarm 1, and alarm 2 relay terminal

strips. They are three-position plug-in style terminal strips. The relay terminal strips are used to connect devices

such as lights and horns that are controlled by the relay contacts. The relay contacts are rated at 115 VAC, 5

amps. The relay contacts may also be used to control higher rated relays.

Termination Jumper

A two pin header with a termination jumper installed is located below the Modbus terminal strip. Leave this

jumper installed unless directed to remove it for a Modbus installation. See “Chapter 8: RS-485 Modbus Output”

on page 61 for a description of using the M2A in a Modbus system.

Ground Jumper

A two pin header with a jumper installed is located along the left side of the terminal PCB. Leave this jumper

installed unless directed to remove it for a Modbus installation. See “Chapter 8: RS-485 Modbus Output” on

page 61 for a description of using the M2A in a Modbus system.

Control PCB

The OLED display and control switches are located on the control PCB. It is installed on top of the terminal PCB

by lining up its three spacing standoffs with the banana jacks in the terminal PCB mounting standoffs and

pushing it onto the banana jacks. The jacks retain the control PCB.

Figure 12: Control PCB Component Location

ENTER

DOWN/NO

UP/YES

Push Button

Control

Switches

Magnetic Switches

ENTER

UP/YES

DOWN/NO

Alarm 1 LED

Alarm 2 LED

Fail LED

RX LED

TX LED

M2A TRANSMITTER

RKI INSTRUMENTS

OLED Display

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RKI Instruments M2A Series Owner's manual

RKI Instruments M2A Series Owner's manual

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